Document and Entity Information - USD ($)	12 Months Ended
	Jul. 31, 2020	Nov. 05, 2020	Jan. 31, 2020
Document And Entity Information
Entity Registrant Name	GENEREX BIOTECHNOLOGY CORP
Entity Central Index Key	0001059784
Current Fiscal Year End Date	--07-31
Entity Filer Category	Non-accelerated Filer
Entity a Well-known Seasoned Issuer	No
Entity a Voluntary Filer	No
Entity's Reporting Status Current	Yes
Entity Incorporation, State or Country Code	DE
Entity Small Business	true
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity File Number	000-29169
Document Type	10-K
Amendment Flag	false
Document Period End Date	Jul. 31, 2020
Document Fiscal Period Focus	FY
Document Fiscal Year Focus	2020
Entity Current Reporting Status	Yes
Entity Common Stock, Shares Outstanding		107,949,089
Entity Public Float			$ 26,808,181
Entity Interactive Data Current	Yes